I have a 350 SBC and as I collect overhaul parts I want to fine tune the Quadrajet that is on it. I don't know a lot about carb theory and operation (I do know the basics). Presently, the engine runs well but it doesn't seem that the 4 bbls are opening up when you step on it (or maybe my cam is just flat worn out too). How can I check this and how do I adjust the 4 bbls too?

I should know this but I don't. Teach me now and I will never ask again (I hope)...

0n the right side of the carb there will be a 3/32 allen set screw you must loosen, You find it on the underside of the boss that exist's near the right rear barrel. Then turn the adjustment screw, tighter will delay the Aux. Air Valve. Any Quad book can show you where it's at. IF you can't find it I'll try to get a picture.

You will know if the secondaries are opening up or not, you will hear the most beautiful roaring sound you have ever heard from a carb.

You can also check to see if they are opening by pushing the throttle linkage to more than 70% (when hot) the secondaries will start to open(the bottom plates, the top just float there), hold the throttle to WOT and they should be open all the way. This is to be done when the car is OFF! Opening the secondaries by hand when the car is at idle is fun, but OMG it will suck the flesh off your face!

The secondaries sometimes do not work if the choke is stuck or not working, the motor has to be warm for it to work, there is a little lever that stops the secondaries from opening.

If you have a bogging, than you need to adjust the air valve spring tention. Previous post explained how to.

Thanx guys. With a little further examination I have come to the conclusion that my carb is in working condition. This whole motor is fairly old and I don't think anything is really bad, just everything is worn. Working on that!! Regardless, I will be putting a new Edelbrock 600 cfm w/electric choke on eventually. I think a new cam/lifter kit is in need here. I may mess around w/ the old q-jet after it is off the truck and see if I can beef it up for some hands on education for myself.

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